1. Field of the Invention
The present invention relates generally to a weft inserting device for guiding weft flying into, for example, an air jet loom, and, more particularly, to a weft inserting device which uses a profiled reed designed to improve the stability of the flying weft.
2. Description of the Related Art
There are two types of conventional weft inserting devices for guiding the flying of weft inserted by an air jet. The first type uses an air guide and the other uses a profiled reed.
Some known weft inserting devices using an air guide are disclosed in Japanese Unexamined Patent Publication Nos. Sho-55-93844 and Sho-57-95344 and Japanese Patent Publication No. Sho-59-26688. In general, those weft inserting devices using an air guide have air guides for guiding the flying of weft, a separate reed, and a supplemental nozzle attached with each air guide to assist in guiding the flying of the weft. Each air guide has a circular or rectangular guide hole or C-shaped guide notch. A plurality of guides are arranged on the front side of the reed to provide guide holes or guide notches along the lengthwise direction of the reed. As the guides are arranged in the lengthwise direction of the reed (in the weft inserting direction), the line of the guide holes or guide notches forms a weft passage where weft flies.
The reed beats the weft after inserting the weft into the weft passage. The guide hole or guide notch of each air guide has a great design freedom with respect to its shape, and the shape and the air injecting position of each supplemental nozzle, which assists the flying of weft, can also be designed freely. It is therefore possible to easily set the ideal shape of the guide hole or guide notch and the ideal arrangement of the supplemental nozzles. A weft inserting device using such air guides has a higher air use efficiency than a weft inserting device that uses a profiled reed, and is thus advantageous for stable weft flying.
In the weft inserting device using air guides, however, every time weft is inserted, the air guides should enter the warp openings, weaving through the warp. The reed beats the weft after inserting the weft. At the time of beating the reed, the air guides should come under the warp. The fast entering or retraction of the air guides in or from the warp openings may damage the warp. Further, the reciprocation of each air guide between the position inside the associated warp opening and the position under the warp involves a larger swinging distance of the sley as compared with the case of the weft inserting device that uses a profiled reed. Therefore, the weft inserting device using air guides has difficulty in functioning at a high velocity.
Some known weft inserting devices using a profiled reed are disclosed in Japanese Unexamined Patent Publication No. Hei-2-53935 and Japanese Unexamined Utility Model Publication No. Hei-3-38378. In general, a weft inserting device using a profiled reed has the general construction shown in FIG. 1 but employs a profiled reed 120 provided with guide notches 140 for guiding the flying of weft Y (see FIG. 1) as shown in FIGS. 27, 28, 29, 30 and 31. When reeds shown in FIGS. 27 to 31 are aligned the line of the guide notches 140 forms a weft passage T, similar to the passage shown in FIG. 1. Each guide notch 140 has a horizontal upper wall 141, a vertical deep wall 142, a lower wall 143 extending toward an opening 146, a curved upper connecting portion 144, which connects the upper wall 141 to the deep wall 142, and a curved lower connecting portion 145, which connects the deep wall 142 to the lower wall 143. Supplemental nozzles 160 (FIG. 27, 28 and 29) for assisting the flying of the weft Y are attached at predetermined intervals along the weft passage T, and have injection holes 161 at their distal ends.
In a weft inserting device using the thus constituted profiled reeds, at the time weft is inserted, only the supplemental nozzles 160 enter the associated warp openings, weaving through the warp, while at the time of beating the reed, only the supplemental nozzles 160 come under the warp from the warp openings. As the supplemental nozzles 160 are thin, the warp is hardly damaged even if the supplemental nozzles 160 move into or out of the warp openings at a high velocity. Further, only the supplemental nozzles 160 smaller than the air guides should move between inside the associated warp openings and under the warp, thus requiring a smaller swinging distance of the sley as compared with the case of the weft inserting device that uses air guides. Therefore, the weft inserting device using a profiled reed is advantageous in increasing the operating speed of the air jet loom. The conventional weft inserting device using the profiled reed 120 shown in FIGS. 27 to 31 however has several shortcomings as will be discussed below.
The radius of curvature of each of the upper connecting portions 144 and the lower connecting portion 145 in FIGS. 27 to 31 is set as large as about 2 mm in consideration of, for example, suppressing the disturbance of the air stream in the weft passage T and facilitating punch-out production using a pressing machine. In the weft inserting device using such a profiled reed, therefore, the flying position of the weft Y flying through the weft passage T varies depending on the position on the wall of the guide notch 140 where the air stream S jetted from the supplemental nozzle 160 hits. Some examples of the change in the flying position of the weft Y will be described with reference to FIGS. 27 to 29, each showing a reed piece 130 from the upstream side in the weft inserting direction.
To begin with, with reference to FIG. 27, a description will be given of the relation between a change in the position of the maximum stream velocity and the flying position Y20 of the weft Y in the case where an air stream S20 hits on the upper wall 141. The "position of the maximum stream velocity" (hereinafter referred to as "maximum stream velocity position") means the position or area at which the air stream flowing through the weft passage T reaches the maximum velocity, and generally coincides with the position or area where an air stream S injected from the supplemental nozzle 160 is present. The air stream S20 injected from the supplemental nozzle 160 hits against the upper wall 141, then proceeds toward the deep wall 142, and changes its course downward along the upper connecting portion 144 to flow toward the opening 146 from the deep wall 142. Accordingly, the maximum stream velocity position also shifts, so that the weft Y is influenced by the downward deflected stream at the upper connecting portion 144 and flies near the lower connecting portion 145 as indicated by the flying position Y20.
Next, with reference to FIG. 28, a description will be given of the relation between the transition of the maximum stream velocity position (the location of an air stream S21) and the flying position Y21 of the weft Y in the case where the air stream S21 strikes on the deep wall 142. The air stream S21 injected from the supplemental nozzle 160 strikes the deep wall 142, then changes its course upward along the upper connecting portion 144, and flows toward the opening 146 from the deep wall 142 along the upper wall 141. Accordingly, the maximum stream velocity position also shifts, so that the weft Y is influenced by the upward deflected stream at the upper connecting portion 144 and flies near the upper wall 141 as indicated by the flying position Y21.
With reference to FIG. 29, a description will now be given of the relation between the transition of the maximum stream velocity position (the location of an air stream S22) and the flying position Y22 of the weft Y in the case where the air stream S22 strikes the upper connecting portion 144. The air stream S22 injected from the supplemental nozzle 160 strikes the upper connecting portion 144, and then flows toward the opening 146 along substantially the same path as the path of the forward movement. Accordingly, the maximum stream velocity position also shifts, so that the weft Y flies near the upper connecting portion 144 as indicated by the flying position Y22.
As apparent from the above description of three cases, the flying velocity of the weft Y and the flying stability of the weft Y are associated with the flying position of the weft Y. In other words, the flying velocity of the weft Y and the flying stability of the weft Y are related to the air stream velocity distribution in the weft passage T.
Therefore, the relation among the flying velocity of the weft Y, the flying stability of the weft Y and the air stream velocity distribution in the weft passage T will be discussed below with reference to FIGS. 30 and 31. FIG. 30 shows the air stream velocity distribution at a position of 60 mm downstream from the supplemental nozzles 160 in the weft passage T when the supplemental nozzles 160 are arranged at intervals of 60 mm, and FIG. 31 shows the air stream velocity distribution at a position of 80 mm downstream from the supplemental nozzles 160 in the weft passage T when the supplemental nozzles 160 are arranged at intervals of 80 mm. The broken lines represent the uniform velocity distribution lines whose intervals indicate the units of 10 meters per second (m/s). The position indicated by Vm is the maximum stream velocity position.
As has been discussed referring to FIG. 27, the air stream S20 directed toward the opening 146 is weak in the vicinity of the flying position Y20, so that the weft Y flying near the flying position Y20 does not fly off the weft passage T, stabilizing the flying state of the weft Y. Since the air stream velocity near the flying position Y20 is lower than he air stream velocity at the maximum stream velocity position Vm, however, the flying velocity of the weft Y flying at the flying position Y20 is slower. It is not therefore possible to increase the flying velocity of the weft Y.
Because the flying position Y21 is near the maximum stream velocity position Vm, the air stream velocity at the position Y21 is close to the maximum velocity so that the flying velocity of the weft Y flying at the flying position Y21 is high. As has been discussed referring to FIG. 28, however, the air stream S21 directed toward the opening 146 is strong in the vicinity of the flying position Y21, so that the weft Y flying near the flying position Y21 is likely to fly off the weft passage T, making the flying state of the weft Y unstable. Therefore, the flying stability of the weft Y cannot be improved.
Further, the flying position Y22 is also near the maximum stream velocity position Vm and the air stream velocity at the position Y22 is thus close to the maximum velocity. That is, the weft Y flies at a high velocity at the flying position Y22. As has been discussed referring to FIG. 29, the air stream S22 directed toward the opening 146 is weak in the vicinity of the flying position Y22, so that the weft Y flying near the flying position Y22 does not fly off the weft passage T. The flying state of the weft Y therefore is stable.
To accomplish the fast and stable flying of the weft Y, therefore, the flying position of the weft Y should be kept at the flying position Y22. For this purpose, it is important to direct the air stream S, injected from the supplemental nozzle 160, toward the upper connecting portion 144 and to allow the weft Y to fly near the upper connecting portion 144. It is, however, inevitable that the installation positions of the supplemental nozzles 160 relative to the weft passage T, the installation angles of the supplemental nozzles 160, and the injecting directions and injection pressures at the injection holes 161 will vary. Actually, the position of the air stream S hitting on the wall of the guide notch 140 changes.
In the weft inserting devices using a profiled reed as described in the aforementioned Japanese Unexamined Patent Publication No. Hei-2-53935 and Japanese Unexamined Utility Model Publication NO. Hei-3-38378, the angle between the upper wall 141 and deep wall 142 of the guide notch 140 is set to a right angle or an acute angle to make the top portion of the weft passage T deeper, thereby suppressing the flow of the air stream S, injected from the supplemental nozzle 160, toward the opening 146. Even when the top portion of the weft passage T is made deeper, however, the upper connecting portion 144 which connects the upper wall 141 to the deep wall 142 dose not permit the weft Y to fly stably in some cases.
According to the conventional weft inserting devices, as described above, increasing the flying velocity of the weft and suppressing the problem of the weft flying off the weft passage cannot be satisfied at the same time.